The differentiated curriculum, which has dominated the organization of public secondary schools in the United States since the turn of the century, changed the course of public secondary education in St. Louis. Prior to the advent of the differentiated curriculum, the course of study in St. Louis high schools was firmly embedded in a strong, academic tradition. It was the schools' objective to guide students in intellectual and moral development. In contrast, the differentiated curriculum, which was implemented at a time when high school enrollments were beginning to sharply increase, diverted attention to vocational preparation and citizenship training. The result was a decline in academic quality. Perhaps of greater consequence, the ideology which ushered in the differentiated curriculum obliterated the notion that all people were worthy of a liberal education. Consequently, the stellar history of St. Louis high school women in the nineteenth century has all but been forgotten. In the early decades of the St. Louis high schools, years which correspond to the academically-dominated curricula, women comprised a considerable majority of both high school students and graduates. After the establishment of the differentiated curriculum, however, female high school students in St. Louis enrolled in fewer academic courses of study. This thesis charts the transformation which occurred in St. Louis high schools from 1870 to 1930. As Henry David Thoreau is often quoted, one can train a scholar or a citizen, but not both. During the period of time covered by this study, St. Louis public high schools abandoned the commitment to nurturing female scholars and joined the twentieth-century fraternity pledged to the task of creating domesticated citizens.